Fluorocarbon ethers of tetrafluoroethylene epoxide



United States Patent 3,250,806 FLUOROCARBON ETHERS OF TETRAFLUORO-ETHYLENE EPOXIDE Joseph Leo Warnell, Wilmington, Del., assignor to E. I.du Pont de Nemours and Company, Wilmington, Del., a corporation ofDelaware No Drawing. Filed Apr. 5, 1962, Ser. No. 185,232

Claims. (Cl. 260-535) The present invention relates to novelfluorocarbon ethers and a method for their production. Morespecifically, the invention relates to fluorocarbon ethers obtained bythe reaction of tetrafluoroethylene epoxide with fluorocarbon acidfluorides.

The novel fluorocarbon ethers of the present invention have the formulawhere X is a halogen or a hydrogen, R, a perfluoroalkylene radical, andpreferably a perfluoroalkylene radical of one to ten carbon atoms, withthe proviso that when X is other than fluorine, R f contains at leasttwo carbon atoms, R"; is a perfluoroalkylene radical of at least twocarbon atoms, and preferably a perfluoroalkylene radical of twoto tencarbon atoms, R"' is a perfluoroalkylene radical, and perferably aperfluoroalkylene radical of one to ten carbon atoms, n and m areintegers representing the number of CF -C-F O-- units in the molecule,said integers being in the range of zero to twenty, and COY is acarboxylic acid group or a carboxylic acid derivative group.

The fluorocarbon ethers .of the present invention are obtained byreacting tetrafluoroethylene epoXide,

C2 G F2 with a substantially fluorinated or perfluorinated acid fluoridewhich can be the fluoride of a monobasic or a dibasic acid, or with asubstantially perfluorinated ketone which can be linear or cyclic instructure. The reaction is carried out in a solvent or diluent attemperatures of 80 to +50 C. with the aid of a catalyst. The catalyst isa quaternary ammonium fluoride, R N+F-, in which R is a hydrocarbonradical, and, preferably, an aliphatic hydrocarbon radical of one toeighteen carbon atoms. Al though the actual catalyst is the quaternaryfluoride, any quaternary ammonium salt having the R N+ radical may beemployed since the quaternary fluoride is formed in situ by reaction ofthe quaternary salt with either the acid fluoride or tetrafluoroethyleneepoxide. The formaticn of the fluoride takes place at all suitablereaction conditions. Thus, such salts are carboxylates, chlorides,iodides, bromides, cyani'des, and quaternary salts of other mono valentanions are suitable. Examples of the quaternary ammonium salts useful inthe present invention are tetraethyl ammonium cyanide, tetraethylammonium bromide, tetrabutyl ammonium acetate, trimethylcetyl ammoniumfluoride, and dimethyl dibutyl ammonium cyanide.

The reaction of tetrafluoroethylene epoxide with the acid fluoride orthe ketone is carried out in a liquid reaction medium alsohereindescribed as a solvent or diluent. The solvents employed areliquid halogenated "ice methyl ammonium fluoride; If the halogenateda-lkane is able to dissolve at least 0.001 weight percent of-thequaternary fluoride at normal temperatures, it can be employed in theprocess of the present invention. This test, therefore, provides asimple method of determining those halogenated alkanes which aresuitable in the process of the invention. The preferred solvents arethose which have the general formula Xc,, F,,,cH,c1, in which X is ahalogen or a hydrogen and p varies from one to eleven carbon atoms.methylene chloride, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane and 1,l,2,3-tetrachloropropane.

The catalyst is normally employed in concentrations of 0.001 to 5percent by weight of the solvent. The solvent is employed in sutiicientquantities to maintain a fluid reaction mixture which can be agitated.No specific pressures are required to carry out the reaction. Optimumpressures are determined by the reaction environment.

The acid fluorides employed as reagents in the described process are, asindicated, acid fluorides of perfluorinated acids andomega-hydroperfluoro acids. A general formula for the monobasic acidfluorides is XC 'F COIF, in which X is a halogen or a hydrogen, and kvaries from zero to nine, with the proviso that when X is other thanfluorine, k is from 1 to 9. The dibasic acid fluorides employed in thedescribed process include the acid fluorides of oxalic acid,perfluoroglutaric acid, 'perfluoromalonic acid, perfluorofumaric acid,perfluorosue cinic acid, perfluoroadipi-c acid, and perfluorosebacicacid. Examples of monobasic acid fluorides are carbonyl fluoride,perfluoroacetyl fluoride, perfluoropropionyl fluoride,perfluoroisobutyryl fluoride, perfluoroheptanoyl fluoride,perfluorodecanoyl fluoride, omega-hydroperfluoroheptanoyl fluoride andomega-hydroperfluoropentanoyl fluoride. The preferred perfluoroketonesuseful in the present invention are perfluoroketones of three to tencarbon atoms such as perfluoroacetone and perfluorocyclohexanone.

One of the advantages of the reaction described is the degree of controlthat can be exercised over the reaction by the ratios of the acidfluoride and the tetrafluoroethylene epoxide. Thus, if a ratio of onemole of the acid fluoride and 5 moles of tetrafluoroethylene epoxide arereacted, the major reaction product contains one mole of the acidfluoride and five moles of tetrafluoroethylene epoxide. Although adistribution of products differing in degree of polymerization, i.e.,number of OF CF --O units, is obtained, this distribution is verynarrow.

In view of the extreme reactivity of tetrafluoroethyleneepoxide, greatcare should be taken in the handling of tetrafluoroe-thylene epoxide.Tetrafluoroethylene epoxi-de, .B.P. 63.5il C., is prepared by oxidizingtetrafluoroethylene with molecular oxygen using actinic radiation and atrace of chlorineor bromine as an activator.

The invention is further illustrated by the following examples.

Examples of other suitable solvents are i Example I To this mixture wasadded 4 g. of telrafluoroethylene epoxide. Complete consumption of theepoxide occurred, indicating the catalyst to be active and beingconverted to a quaternary ammonium fluoride. There was then added insequence 20 g. of perfluoroacetyl fluoride and 40 g. oftetrafluoroethylene epoxide at 30' p.s.i. After the reaction wascomplete, there was added an additional 79 g. of perfluoroacetylfluoride and then 286 g. of tetrafluoroethylene epoxide at 15-20 p.s.i.Complete reaction occurred in three hours. The final mole ratio oftetrafluoroethylene epoxide to perfluoroacetyl fluoride charged was3.311. After removal of residual small amounts of perfluoroacetylfluoride and tetrafiuoroethylene epoxide, there was isolated 410 g. ofproduct that, on distillation, yielded:

Fraction Weight, Structure Boiling 1 point, C.

15 oirsoortoor 04s 103 C2F50 (C2F40)3O E2COF- 134-138 33 CzFsO (C2F40)4GF2C' OF- 167-170 B.P. 9798 C. at 16 mm.

Analysis.-Found: F, 60.0; neutral equivalent 462.

CalccL: F, 61.8 neutral equivalent 462.

v 1 The use of trimethylcetyl ammonium bromide instead of thetetraethylammonium cyanide in the described pro- .cedure gives rise tosubstantially the same result.

Example 11 A 500 ml. copper reactor, containing a magnetic stirrer andattached to a manifold, was cooled to 50 C. and charged with 0.4 g. oftetraethylamni-onium cyanide and 20 ml. of CHF CF CH CL There was thenadded 3 g.--of tetrafluoroethylene epoxide which was rapidly consumed.There'was then added 10 g. of periluoroethoxyacetyl fluoride mixed with40 g. of perfluoroacetyl 'fluoride followed by a total of 221 g. oftetrafluoroethylene epoxide at 30 p.s.i. while the reaction mixture wasstirred rapidly at 30 to 15 C. over one hour. Complete absorption of theepoxide occured. There was isolated 269 g. of product having the generalstructure C =F O(OF OF O), OF COF, where n varied from zero to six.

Over 80% of the product consisted of compounds wherein n was three,four, and five. The products were identified by gas chromatography andinfrared spectra.

Example 111 I Example .I is repeated using tetraethylammonium bromide asthe catalyst and methylene chloride as the solvent. Essentially the sameproduct distribution is obtained.

4 Example IV Using the procedure of Example I, carbonyl fluoride isreacted with tetrafluoroethylene epoxide using tetraethyl-ammoniumcyanide at the catalyst, and

HCF OF CF CF CH Cl The product has the structure CF 0 (CF CF O CF COFwhere the value of'n is determined by the molar ratio of carbonylfluoride to tetrafluoroethylene epoxide. Thus, a charge consisting of0.1 mole of carbonyl fluoride and 0.5 mole of tetrafiuoroethyleneepoxide gives a product containing over 70% of tetrafluoroethyleneepoxide po-lyethers of the formula indicated above in which n is three,four, and five. The products are identified by as the solvent.

' gas chromatography, nuclear magnetic resonance (NMR), and infraredspectra as CF 0 (CF OF O CF 'CO-F Example V Using the procedure ofExample I, perfiuoropropionyl fluoride is reacted withtetrafluoroethylene epoxide using tetraethylammonium cyanide as thecatalyst, and

HCFgOFgCFgC'FzCHzCl as the solvent. The product has the structure CF CF01 0 (CF CF O C-F COF wherein the value of n is determined by the molarratio Example VI Use of dichloroethane, as a solvent, in the procedureof Example IV, gives rise to essentially identical results.

Example VII In a 500 ml. copper reactor containing a magnetic stirrerand attached to a manifold was placed 0.25 g. of tetraethylammoniumcyanide. The reactor was cooled to '80 C. and there was added 15 m1. of

and about 1 g. of tetrafluoroethylene epoxide. The reaction mixture waswarmed to 20 C. at which temperature consumption of the epoxideoccurred. The mixture was cooled to C. and 34 g. of penfiuorog-lutarylfluoride was added. The mixture was warmed [to 35 C. and 66 g. oftetrafiuoroethylene epoxide was added over minutes at 8-15 p.s.i.Complete reaction occurred. The molar ratio of glutaryl fluoride totetrafluoroethylene oxide charged was 124. There was isolated 122 g. ofproduct containing 21 g. o-f'solvent. The crude product was added to ml.of methanol at 0 C. Complete conversion to methyl esters occurred. Themethanol was removed by distillation and the residual fluorocarbonfraction was treated with silica gel to remove HF. The product was thendistilled to givea series of fractions boiling from 133 C. at 26 mm. to

'of OH 'O C(CF (CF CF 0) CF CO CH and products of the type where I hadvalues from zero to five and m and a had 75 values from one to three.The products were characterized by infrared, NMR, and elementalanalyses. Typical cyanide and 20 ml. of CHF CF CH Cl. Reaction atanalyses are indicated below. -35 C. of the stirred solution with 2 g.of tetrafluoro- Product Anal. found Anal. calcd.

CH302C(CF2)4OCF2CF2OCF2CO2CH3and C. 27.7 0,215.4.CH302CCF20(CF2)5OCF2CO2CH3. g. 1 2 1 1, 1CHaOzC(CF2)40(CFzCFzOMCFzCOzCHa and C, 24. C, 25.4. CHaOzCCFzO (CF2)50OFECFZOCFZC OzCHa. g, 5.92 g, i CH3O2C(CF2)4O (CFzCFzOhCFzCOzCHa and C,24.4 C. 24.5. CH3O2GCF O(CF2)5O(CF CFgOhCFzCOzCHa and H, 0.7 H, 0.8. CHO CCFCFzCFgO(CFDs FzCFzOCFzCOgCHa. F, 55.2 F, 57.2.

Example VIII Using the procedure of Example VII, 49 g. ofperfluoroglutaryl fluoride was reacted with 206 g. oftetrafluoroethylene epoxide at 40 to 20 C. A quantitative yield of amixture of products of the structure was obtained where over 90% of theproduct had values of m+n from four to eight. These compounds werereadily converted by the usual methods to diesters, diamides and salts.

Example IX In a dry glass fiask containing a magnetic stirrer andattached to a manifold was placed 0.2 g. of tetraethylammonium cyanide.There was added 5 ml. of

at 50 C. A small quantity of tetrafluoroethylene epoxide was added andthe temperature was warmed to 20 C., at which temperature completeconsumption occurred. There was then added 6 g. of oxalyl fluoride. Thetemperature was raised to 04 C. and 13 g. of tetrafluoroethylene epoxideat 10 psi. was added over a period of 2.5 hours. There was isolated 12.8g. of liquid product together with 6 g. of gaseous material.Distillation of the entire mixture gave small amounts oftet-rafluoroethylene epoxide, oxalyl fluoride, perfluoroacetyl fluoride,and some homopolymers of tetrafluoroethylene epoxide of structure CF CFO(CF CF O) CF COF.

The major product comprises reaction products of tetrafluoroethyleneepoxide and oxalyl fluoride having the general formula FOCCF OCF CF OCFCOF the composition of which is indicated below.

Weight, g.

The identity of these products was shown by gas chromatography andinfrared analysis.

Example X Using the procedure of Example I hexafluoroacetone is reactedwith tetrafiuoroethylene epoxide. On distillation of the reactionproduct the principal fluorocarbon ether fraction B.P. 39-42 C. islargely Into a dry flask, equipped with a magnetic stirrer and a coolingbath, was added 250 mg. of tetraethylammonium Compound Weight, g.Boiling point. C.

BrOF2CF2OOF2COF 7 52 to 62. Br-(CFzCF2O)2OF2COF.- 8. 5 to 103.Br(CFzCFzO)aGF2COF 10 133 to 136. g 2gg28g28g4 8g2g8g 11.5 164 to 169. 22 2 Br(C F2CF20) -CF2COF i 12 Analyses.-Theory for C F O Br: C, 16.4; F,45.3. Found: C, 16.84; F, 45.44.

Theory for C F O Br: C, 17.6; F, 51.0. Found: C, 17.84; F, 50.9.

Theory for Br(CF CF O) CF COF: C, 19.0; F, 57.6. Found: C, 19.85; F,57.98.

Similar products are obtained by reaction of ICF CO'F or HCF COF withtetrafluoroethylene epoxide under comparable conditions.

Example XII To a clean, dry reactor was added 300 mg. oftetraethylammonium cyanide; the reactor was then attached toa manifoldand heated under vacuum at 60 C. for 5-10 minutes. After the reactor hadbeen cooled, 14 ml. of HCFgCPgCHgCl was added as solvent, and the systemwas cooled to -35. Tetrafluoroethylene epoxide was then pressured intothe reactor until reaction had begun, as evidenced by a rapid pressuredrop after each addition of tetrafiuoroethylene epoxide. The system wasthen cooled to 50 C., and 29.8 g. (0.225 mole) of chlorodi- 0fluoroacetyl fluoride was added. The temperature of the system was thenmaintained at 35 to 40 C. while 70 g. (0.6 mole) of tetrafluoroethyleneepoxide was pressured in over a period of 45 minutes. Constant magneticstirring was maintained throughout the reaction. After alltetrafl'uoroethylene epoxide had been added, the reaction mixture wasallowed to warm gradually to room temperature; the pressure was then 10"vac. The crude product (98% yield, based on acid fluoride) was distilledin a small spinning band column, and the following pure components wereisolated and identified.

Compound B.P., Weight, Converdeg. g. sion 1 OICFZCF2OCF2COF 45 3. 5 6.2ClCFzCFzOCFzCFzOCFzCOF 91-93 13. 5 16. 5 C1CF2CF20(CF20F20 2CF2OOF129-130 10. 6 9. 8 C1CF2CF20(OF2GF20)3CF2OOF 149-150 13. 6 10.1

1 Based on acid fluoride charged.

useful as such or as intermediates.

Each of the above products was further purified by preparative gaschromatography; the NMR and infrared spectra of the pure samplesconfirmed the structure of each of the products.

The foregoing examples have illustrated the preparation of novelfluorocarbon ethers and are not intended to limit the scope of theinvention. Substitution of catalysts, solvents and acid fluorides otherthan employed in the examples but described hereinabove, in theprocedures set forth in the examples will resultin the three types offluorocarbon ethers which are formed by the reaction of monoor dibasicacid fluorides with tetrafluoroethylene epoxide. The fluorocarbon etherof type I is formed by the reaction of a monobasic acid fluoride withthe epoxide, type II is formed by the reaction of the epoxide with bothacid fluoride groups of a dibasic acid fluoride and type III is formedby the reaction of the epoxide with a single acid fluoride group of adicarboxylic acid. As indicated, the monobasic acid fluoride may alsocontain a hydrogen or a different halogen in the omega position. Acidfluorides of this type exhibit substantially the same chemical activityas perfluorinated acid fluorides and are, therefore, considered to be ofthe same class.

The fluorocarbon ethers produced by the process of the present inventioncontain acid fluoride endgroups. As illustrated by the examples, theseacid fluoride endgroups are readily converted into acid endgroups. Thefluorocarbon ether acids can be reacted with alcohols, inorganic bases,basic salts and amines to result in carboxylic acid derivatives of thetype normally formed with fluorocarbon carboxylic acids which are wellknown in. the art. The term carboxylic acid derivative is meant toinclude. only those derivatives which have retained the carbonyl groupof the acid. The reactivity of the acid group of the fluorocarbonpolye-thers of the present invention is equivalent to the reactivity ofa fluorocarbon carboxylic acid having the same number of carbon atoms.

The fluorocarbon ethers of the present invention are In their acid orsalt form these fluorocarbon ethers are useful detergents. They may alsobe employed as solvents or as heat transfer and dielectric media. Insuch uses, however, it is preferred to replace the COY group with afluorine which is accomplished by decarboxylation of the fluorocarbonether acid in the presence of fluorine. The resulting fluorine cappedproducts are enhanced in chemical inertness.

Similar products of inherent chemical inertness are obtained bydecomposition of alkali metal salts of the acids in the presence ofhydroxylic solvents. These products have COY groups replaced by hydrogenatoms.

8 I claim: 1. A fluorocarbon ether having the formula where R" is aperfluoroalkylene radical of two to ten carbon atoms, 11 and m areintegers of zero to twenty and COY is a group selected from the classconsisting of the carboxylic acid group and the carboxylic acid fluoridegroup.

2. A fluorocarbon ether having the formula where R, is aperfluoroalkylene radical of one to ten carbon atoms, 22 is an integerof zero to twenty and COY is a group selected from the class consistingof the carboxylic acid group and the carboxylic acid fluoride group. I

3. A fluorocarbon ether having the formula where n is from zero totwenty and COY is a group selected from the class consisting of thecarboxylic acid group and the carboxylic acid fluoride group.

4. A fluorocarbon ether having the formula where n is from zero totwenty and COY is a group selected from the class consisting of thecarboxylic acid group and the carboxylic acid fluoride group.

5. The fluorocarbon ether having the formula where n is from zero totwenty, COY is a group selected from the class consisting of thecarboxylic acid group and the carboxylic acid fluoride group, and X isan element selected from the class consisting of chlorine,

bromine, iodine and hydrogen.

References Cited by the Examiner LORRAINE A. WEINBERGER, PrimaryExaminer.

DANIEL D. HORWITZ, LEON ZITVER, D. P. CLARKE, R. K. JACKSON, AssistantExaminers.

1. A FLUOROCARBON ETHER HAVING THE FORMULA
 2. A FLUOROCARBON ETHERHAVING THE FORMULA
 3. A GLUOROCARBON ETHER HAVING THE FORMULA
 4. AFLUOROCARBON ETHER HAVING THE FORMULA
 5. THE FLUOROCARBON ETHER HAVINGTHE FORMULA